By Yuval Kapellner Rabinovitz

Texas Instruments (TI) DLP Technology has been a world renowned technology
for many years with its various current applications in business office
and theater video projectors.
The DMD (Digital Micro Mirror Device) is the key component that serves as the core
of the digital light processing technology made
of fabricated MEMS array in a mirror
formation which utilize components
in different mirrors available in various sizes (8um-11um)
dependent on the type of modulator.

DMD belongs to a category of SLM which divert light in mirror/pixel levels allowing
a tilt angle per mirror between +-12 degrees simultaneously performing modulation of
the propagating light in amplitude level that can translate to a static or motion
image when supported with imaging optics.

In recent years, there have been great changes in integration of projection engines
in new applications. A trend in implementing these light engines is evolving in commercial
and industrial applications. The popular growing application is Micro/Pico projection
which is a miniature video projector that can project large image displays out of small
devices such as portable light weight electronic devices.
Efficiency in mobile electronics
is essential in reducing size and heat dissipation while maximizing the operating time of
small sized batteries. The DMD is a miniature component that can modulate
light while maintaining high optical and electrical efficiency that makes this technology
an attractive solution in mobile devices.

For example, a DMD from the DLP1700 mini series (0.17", 0.3") is a miniaturized version
designed by TI for the Pico projection market. Reflectivity of the mirrors is
approximately 90% consisting of a fill factor of 92% with low electrical
energy consumption (~84mw). Use of polarization became an efficiency barrier issue in different
SLMs (LCOS, LCD) in the recent years with various companies that seek to bypass this requirement
by utilizing polarized light sources (lasers) to improve optical efficiency and tackle
the 50% efficiency drop off with conventional polarizers in those modulators.
One of the many advantages of the DMD is it does not require usage of polarization
to function in modulating the light, and it holds capabilities to perform under high powered
illumination. DMD does not produce unwanted artifacts often seen in LCOS and LCD spatial light
modulators which usually require special heat shielding in comparison.

However, functionality of the LCOS and LCD SLMs are still polarization dependent
while the 3D projection evolution grows with no dependency on polarization,
but could use polarized light for different purposes separate from its own functionality
in producing amplitude light modulation. This could serve in purposes of producing images
changes commanding different polarization positions in 3D image production while polarization
is being manipulated at the light source level.

Until recently, there was no real significance on whether the SLM could cover
a wide wavelength range since most of the conventional SLMs were applied in
projection engines in the visible spectrum. Having an SLM able to modulate light
at VIS was more than enough for most applications. However, many of the companies
that use SLMs have been looking for options to overcome the high optical power propagating
the SLMs to reduce unwanted TFT effects inside the modulators. Before the time
of HB-LEDs when high power light bulbs where dominating the conventional light
engine in video projection, IR filters were used to reduce accumulated heat from
the surface of the SLM and minimize unwanted effects on its performance.

The DMD technology is capable of working in a wide spectrum of wavelengths
and this device have a significant advantage previously unrecognized until recently
when new applications have evolved requiring use beyond VIS or simultaneously with VIS
or other wavelengths across the spectrum. DMD technology has become a popular
demand especially in commercial applications. As the trend continue towards 3D modeling
applications, soon it will be possible to see this combining with VIS projection
engines that are blended together with NIR that would allow user interactivity
with the projected data.

In 2011, evidence of an emerging demand can be seen in combining optical
projection channels and sensors in devices such as cameras with a closed
loop system especially in the field of image modeling of 3D structures
(structured light applications). As the 3D mode thrives to dominate grabbing
of 3D objects and projection of 3D data, there are strong growths of these
applications in a variety of commercial and entertainment electronics entering
into new market sections in the industry beyond conventional image projection
ever known before. This is also true in invisible wavelength ranges at NIR and UV
with propagating requirements for DUV especially for data applications and wafer
inspections in the high tech industry.

Frame refresh value is an issue with the sensor and projection levels in new applications
requiring image grabbing of fast moving objects for 3D modeling that requires both
channels to work quickly to obtain high sampling frequency of the objects.
Depending on the model type, the DMD solution can work at several KHz as high as 32KHz
with high refresh rates which presents many options for integrating the DMD as
a high optical switch that could quickly toggle between different optical channels
for projecting and/or sensing.

EKB Technologies LTD, an Israeli company, has successfully utilized the DMD
to manipulate the phase of the light rather than amplitude to produce binary
diffractive optical element in a lens free optical setup.
This utilization of the DMD allows EKB to cut down risks in design and production
of complicated diffractive optical elements (i.e. phase masks).

“Working with a variety of wavelengths opens new opportunities in new
applications in different markets from commercial to military and medical fields”,
says Sharon Kapellner Rabinovitz, Founder and CEO of EKB Technologies LTD.

A new leap in the vision of technology in miniature projection systems with VIS and NIR
spectrums continue to emerge as it is expected to reach higher demands in the
coming years when more light projection engines will be integrated in a variety of
applications such as face recognition alarm systems, virtual keypads,
material inspection systems, intercoms, vehicles with driver recognition and data projection,
and digital cameras that allow recording of distance and physical measurements before the data
can actually be saved or recorded. For example, using a closed loop projection system in
devices such as mobile phones could become a measuring tool to capture an image of a furniture
at a store which the system can then calculate the dimensions to determine the fit of the
furniture for a designated area in a home.

Other systems such as ATMs could utilize similar modules to allow
user operation by "virtual touch" on a true touchless display integrated
with VIS and NIR projection engine in one module.
Virtual display does not have to originate from a specific frame or structure as it is
becoming more natural to blend with the user by sensing user movements to project
the information on surface(s) of possibly different shapes each time.
One of its many useful applications can be valued in the medical field
in ways the system could project information on the patient while simultaneously
adjusting to stabilize itself with the data location of the patient’s body as he/she moves.
Interactivity with user is the future with more applications emerging that would give
support in that level.

This April presents a great opportunity as DLP experts arrive in Israel
from Texas Instruments corporate headquarters located in the USA in collaboration with
EKB Technologies LTD to promote DLP familiarity in the Israeli high tech industry.